Valves are commonly used in devices that involve the transportation of a fluid. A typical type of valve, for example used in laboratory systems of moderate sizes, is the rotary valve.
Generally, a rotary valve has a stationary body, herein called a stator, which co-operates with a rotating body, herein called a rotor.
The stator is provided with a number of inlet and outlet ports. The ports are via bores in fluid communication with a corresponding set of orifices on an inner stator face. The inner stator face is an inner surface of the stator that is in fluid tight contact with an inner rotor face of the rotor. The rotor is typically formed as a disc and the inner rotor face is pressed against the inner stator face in rotating co-operation. The inner rotor face is provided with one or more grooves which interconnect different orifices depending on the rotary position of the rotor with respect to the stator.
Rotary valves can be designed to withstand high pressures (such as pressures above 25 MPa). They can be made from a range of materials, such as stainless steel, high performance polymeric materials and ceramics.
The number of inlets/outlets as well as the design of grooves in the rotor or the stator reflects the intended use of a specific valve. A common type of multi-purpose valve has one inlet port (typically placed in the rotary axis of the valve) and a number of outlets ports that are placed equidistantly around the inlet port. The rotor has a single, radially extending groove that has one end in the rotary centre, thereby always connecting to the inlet, while the other end connects to any one of the outlets depending on the angular position of the rotor with respect to the stator. Such a valve is useful to direct a flow from the inlet to any of the outlets—one at a time.
In chromatography systems for continuous chromatography, such as simulated moving bed systems usually a large number of valves are used for providing feed and buffer to the different columns in the system in correct order. There is a need for better valve arrangements in such systems.